Chapter 9: Hydrocarbons — Online MCQ Test
CHEMISTRY · Grade 11 · CBSE(NCERT)
Practice Chapter 9: Hydrocarbons with a free chapter-wise online MCQ test.
This chapter covers: Alkanes Alkenes Alkynes Aromatic hydrocarbons Benzene Saturated Unsaturated Addition reaction Substitution reaction Combustion Cracking.
AI-generated questions from basic to board-exam level, with instant results and explanations.
Chapter 9: Hydrocarbons — Important Questions & Answers
Which of the following is an alkane?
- A. Ethene
- B. Ethyne
- C. Ethane
- D. Benzene
Answer: C. Ethane
Ethane is a saturated hydrocarbon containing only single bonds. Ethene and ethyne are unsaturated, while benzene is aromatic.
Ethane is a saturated hydrocarbon containing only single bonds. Ethene and ethyne are unsaturated, while benzene is aromatic.
The general formula of alkenes is:
- A. C_nH_2n+2
- B. C_nH_2n
- C. C_nH_2n-2
- D. C_nH_n
Answer: B. C_nH_2n
Alkenes are open-chain hydrocarbons with one double bond, and their general formula is C_nH_2n.
Alkenes are open-chain hydrocarbons with one double bond, and their general formula is C_nH_2n.
An alkene is converted into an alkane by which type of reaction?
- A. Substitution
- B. Addition of hydrogen
- C. Elimination
- D. Combustion
Answer: B. Addition of hydrogen
Hydrogen adds across the double bond in hydrogenation, converting an alkene to an alkane.
Hydrogen adds across the double bond in hydrogenation, converting an alkene to an alkane.
A hydrocarbon does not decolourise bromine water at room temperature. Which conclusion is most appropriate?
- A. It must be an alkene
- B. It must be an alkyne
- C. It may be an alkane or benzene under ordinary conditions
- D. It must contain oxygen
Answer: C. It may be an alkane or benzene under ordinary conditions
Alkanes do not react with bromine water without UV light, and benzene also does not readily decolourise bromine water without a catalyst.
Alkanes do not react with bromine water without UV light, and benzene also does not readily decolourise bromine water without a catalyst.
A hydrocarbon has molecular formula C4H8. Which inference is most correct?
- A. It must be an alkane
- B. It can be an alkene or cycloalkane
- C. It must be an alkyne
- D. It must be benzene
Answer: B. It can be an alkene or cycloalkane
C4H8 fits the general formula C_nH_2n, which is shared by alkenes and cycloalkanes. Formula alone cannot distinguish them.
C4H8 fits the general formula C_nH_2n, which is shared by alkenes and cycloalkanes. Formula alone cannot distinguish them.